import java.util.ArrayList;
import java.util.Arrays;
import java.util.Scanner;


public class solver {
    static int n;
    static int[] known;
    static int[] shP;

    static boolean exist(String[] arr, String name){
        for(int i=0;i<arr.length;i++){
            if(arr[i].equals(name)) return true;
        }
        return false;
    }

    static void solve(int[] known, int[] shP, int[][] list,ArrayList<Integer>[] adj, int src){
        known[src] = 1;
        //shP[src] = 0;
        for(int i=0;i<adj[src].size();i++){
            int we = adj[src].get(i);
            if( shP[we] > list[src][we]){
                shP[we] = list[src][we];
            }
        }

        int min = 999999;
        int indexTemp =0;
        for(int i=0;i<shP.length;i++){
            if(shP[i]<min) {
                min = shP[i];
                indexTemp = i;
            }
        }
        solve(known, shP, list,adj, indexTemp);
    }


    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);

        n = in.nextInt(); //nr of vertex
        known = new int[n];
        shP = new int[n];

        Edge[] edges = new Edge[n];


        for(int i=0;i<n;i++) shP[i] = (int) Double.POSITIVE_INFINITY;

        for(int i=0; i<n;i++){
            String c1 = in.next();
            String c2 = in.next();
            int w = in.nextInt();
            edges[i]= new Edge(c1, c2, w);
        }

        int cnt=0;
        String[] V = new String[n];
        for(int i=0;i<n;i++) V[i]="";

        int [][] list = new int[n][n];

        for(int i=0;i<n;i++) {
            for(int j=0;j<n;j++){
                list[i][j]= (int) Double.POSITIVE_INFINITY;
            }
        }

        ArrayList<Integer>[] adj = (ArrayList<Integer>[])new ArrayList[n];
        for(int i=0; i<n;i++){
            String c1 = edges[i].from;
            String c2 = edges[i].target;

            if(!exist(V, c1)){
                V[cnt] = c1;
                cnt++;
            }
            if(!exist(V, c2)){
                V[cnt] = c2;
                cnt++;
            }

            int indOfc1 = Arrays.asList(V).indexOf(c1);
            int indOfc2 = Arrays.asList(V).indexOf(c2);

            if(adj[indOfc1] == null) adj[indOfc1] = new ArrayList<Integer>();
            adj[indOfc1].add(indOfc2);

            list[indOfc1][indOfc2] = edges[i].weight;
        }

        String source = in.next();
        String dest = in.next();
        int indOfsrc = Arrays.asList(V).indexOf(source);
        int indOfdest = Arrays.asList(V).indexOf(dest);

        solve(known, shP, list,adj, indOfsrc);

        System.out.print(shP[indOfdest]);
    }

}
class Edge{
    String from;
    String target;
    int weight;
    Edge(String s, String t, int w){
        from = s;
        target = t;
        weight = w;
    }
}